This invention relates in general to electronically controlled vehicular brake systems. In particular, this invention is concerned with a hydraulic control unit for a vehicular brake system having a control valve that controls fluid from a master cylinder to an inlet of a pump.
Electronically controlled vehicular brake systems may include anti-lock, traction control, and vehicle stability control functions. During various braking functions, such as vehicle stability control (VSC), a pump is activated to provide high-pressure fluid to a wheel brake. For certain events, the pump draws fluid from a master cylinder. A normally closed supply valve is positioned in a hydraulic connection between the master cylinder and an inlet to the pump. During a various braking events, the supply valve is opened so that the pump draws fluid from the master cylinder.
During a vehicle stability control event, a driver may have applied the brake pedal, thereby pressurizing fluid in master cylinder. The VSC supply valve must be able to open under such relatively high-pressure situations so that fluid can be drawn to the pump and supplied to wheel brakes.